Photochemical degradation of acrolein using VUV excimer lamp in air at atmospheric pressure

• Published in: International journal of environmental science and technology (Tehran) Vol. 16; no. 11; pp. 7229 - 7240
• Main Authors: Tsuji, M., Miyano, M., Kamo, N., Kawahara, T., Uto, K., Hayashi, J., Tsuji, T.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.11.2019
• Subjects: Aquatic Pollution; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Science and Engineering; Original Paper; Soil Science & Conservation; Waste Water Technology; Water Management; Water Pollution Control; Acrolein; VOC degradation; VUV excimer lamp; Photooxidation; Catalyst free
• ISSN: 1735-1472; 1735-2630
• DOI: 10.1007/s13762-019-02404-5

The photochemical degradation of acrolein (C 2 H 3 CHO) was investigated in air at atmospheric pressure using a 172-nm Xe 2 excimer lamp. When C 2 H 3 CHO was decomposed using the side-on type of lamp, HCOOH, CO, CO 2 , and O 3 peaks were observed in FTIR absorption spectra. The dependence of product concentrations on the irradiation time indicated that HCOOH and CO intermediates are finally converted to CO 2 via consecutive reactions. The degradation rate coefficient of C 2 H 3 CHO in the batch system increased from 8.4 to 19.3 min −1 , as the O 2 concentration was decreased from 20 to 1%. It increased also from 8.4 to 40.1 min −1 at 20% O 2 , as the chamber depth was decreased from 3.0 to 0.5 cm. The best energy efficiency of the C 2 H 3 CHO degradation was 3.4 g kW −1  h −1 at 1–20% O 2 in a flow system. Besides direct VUV photodissociation of C 2 H 3 CHO, reactions of O( 3 P, 1 D) and O 3 , produced from photolysis of O 2 , can contribute to C 2 H 3 CHO degradation in the initial stage. Among them, the contribution of O( 1 D) and O 3 was found to be insignificant on the basis of the total pressure dependence of removal amount of C 2 H 3 CHO and results obtained from the O 3  + C 2 H 3 CHO reaction. It was concluded that at first C 2 H 3 CHO is decomposed by direct VUV photodissociation of C 2 H 3 CHO and the O( 3 P) + C 2 H 3 CHO reaction. It was further decomposed by secondary reactions of O( 3 P), OH, and O 3 with such intermediates as HCOOH and CO and finally oxidized to CO 2 .